_DeviceDiscoveryUI_SwiftUI cross-import overlay

This cross-import overlay bridges DeviceDiscoveryUI and SwiftUI, exposing the device discovery and advertising experience as SwiftUI controls. With it you advertise your app as discoverable and present a picker for nearby local devices, then establish peer-to-peer communication with a selected device. The overlay defines no types of its own; it adds SwiftUI integration to the underlying DeviceDiscoveryUI APIs on iOS and tvOS.